1. Field of the Invention
This invention relates, generally, to Braille readers. More particularly, it relates to a Braille reader that captures information displayed on a computer screen and transforms the information into Braille.
2. Description of the Background
Electronic devices that capture written information on a computer screen and transform the information into Braille are known. The known devices incorporate Braille cells that may include a plurality of hollow housings of parallelepiped construction, each of which houses either six (6) or eight (8) Braille pins. In the alternative, the housings may be solid and provided with bores for receiving the Braille pins. The pins are arranged in two (2) columns of three (3) or four (4) pins each.
When in repose, each pin is fully positioned within the hollow interior of its housing) or its bore. One of the walls of the housing has six (6) or eight (8) openings formed therein through which the uppermost tips of the pins selectively extend when activated.
The pins are selectively extended by actuator means to represent Braille characters. For example, when the letter “A” is detected on a computer screen, an electrical signal is sent to an actuator and the combination of pins that represents that letter in Braille is activated so that the combination of pins representing that letter are actuated so that they physically extend outwardly of tie housing so that they can be felt by a person reading Braille.
A bimorph reed, sometimes simply called a bimorph or a bimorph actuator, has s common center conductor sandwiched between two piezoceramic transducers. Series polled bimorph reeds are in common use in Braille cell actuators. Prior art Braille cell actuators incorporate series x-polled bimorph reed technology whereby the top and bottom elements are not electrically isolated from one another. The common center point is grounded and a high voltage is applied to one of the outer strips. A simple circuit drives the center conductor and fixes the outer conductor. This arrangement drives only one piezo element and the opposing element performs as a mechanical drag. Hence a bend is formed in the bimorph reed due to the difference in voltage-dependent expansion rates of the two parts of the bimorph reed, just as a bend is formed due to the difference in temperature-dependent expansion rates of the two parts of a bimetallic strip of the type commonly found in analog thermostats
A special metallic plating is applied to the outer piezo-ceramic contacts to enable soldering of the leads to a printed circuit board (PCB). The need for such special metallic plating increases the manufacturing costs associated with each bimorph reed.
Accordingly, there is a need for an improved bimorph reed construction that does not require such special metallic platting.
Sixteen (16) hand-soldered wires requiring thirty-two (32) solder joints are necessary to establish the electrical connections.
Thus there is a need for an improved means for connecting the leads to the PCB. Tie improved means would reduce the number of solder joints required and thus lower the manufacturing costs while increasing the reliability of the Braille cell.
Prior art Braille cells employ one individual cap per individual Braille cell. This results in a reading surface that is rough because it includes grooves, gaps and steps between the individual caps. The individual tolerances of each Braille cell results in a gap between the Braille cells and their surrounding enclosure. Moreover, the assembly of each Braille cell cap drives up the cost of manufacturing.
More particularly, prior art Braille cells employ one individual tactile pin cap per individual Braille cell. The tactile pin cap serves to position and align the pins and further provides cursor control buttons. The Braille cells and associated tactile pin caps positioned adjacent to each other collectively form the tactile surface. The use of individual cell caps for each Braille cell increases the manufacturing cost as aforesaid as well as the cost of materials. Additional stabilizers are required to position and align the individual cell caps. Strict tolerances are required to provide an acceptable tactile feel for the reader. The reader is sensitive to the separation that is inherent between each cell with this design. This unevenness between each cell is a limitation of all Braille displays heretofore known. To tactile users, the tactility of the grooves and cell-to-cell unevenness is comparable to the noise or flicker on a computer monitor experienced by a sighted user. Additionally, maintenance and replacement of the individual tactile pins is often necessary. Contaminants that build up on the pins must be removed or the pins must be replaced upon excessive wear.
Accordingly, there is a need in the art for an improved electromechanical tactile cell for use in a refreshable Braille display. Improvements in manufacturability and reparability are necessary in addition to enhancements in the tactile experience of the user.
The time required to manufacture a plurality of caps, each of which must be within certain tolerance limits, and to individually cap each Braille cell drives up the cost of manufacturing. Prior art cell caps produce a gap between the Braille module and the opening in the Braille display case. Each gap is a result of the accumulation of dimensional tolerances on a per cell basis. The art teaches use of an extra frame to correctly space each cell at a centerline. This approach is unsatisfactory because it further accentuates the unevenness of the display and provides additional area for contaminates.
It would therefore be advantageous if a better way could be found to cover the Braille cells.
The mounting of bimorph reeds has also been a source of problems. Some Braille cell assemblies employ adhesives to adhere the bimorph reeds to a printed circuit board. Some use clamps which themselves must be adhered or otherwise attached to a suitable mounting surface.
Thus there is also a need for an improved means for mounting a bimorph reed to a Braille cell assembly.
However, in view of the prior art considered as a whole at the time the present indention was made, it was not obvious to those of ordinary skill in this field that the identified improvements should be made nor would it have been obvious as to how to make the improvements if the need for such improvements had been perceived.
The longstanding but heretofore unfulfilled need for an improved Braille cell and Braille cell cap assembly is now met by a new, useful, and non-obvious invention. The electromechanical Braille cell assembly of the present invention and the improved Braille cell cap of this invention provides manufacturing cost reductions and substantial improvements in utility and reliability over prior art Braille cell and Braille cell cap assemblies. The present invention also reduces the labor required to manufacture the Braille cell and Braille cell cap assemblies, thereby further reducing the cost of the device.
More particularly, the present invention obviates the need for thirty-two (32) hand-soldered joints and for the routing of sixteen (16) jumper wires, thereby facilitating the manufacturing process and improving the reliability of the product. Additional manufacturing improvements are realized through improved alignment between the Braille pins and the bimorph reeds, also known as bimorph strips or bimorph actuators or simply bimorphs.
The novel Braille cell assembly includes a universal mounting means forming a part of an Original Electronic Manufacturer (OEM) solution. The novel Braille assembly therefore defines a standard for interfacing with the assembly.
More particularly, the novel Braille cell assembly includes a plurality of parallel polled bimorph reeds. Each bimorph reed or strip includes a top plate, a bottom plate, and a center conductor strip sandwiched therebetween. A virtual bimorph ground is provided by grounding the center conductor, by electrically isolating the top and bottom plate from each other, and by applying a high voltage to both the top and bottom plates so that neither plate is a mechanical drag on the other as in prior art bimorph strips.
A novel clip mounts each bimorph reed to a printed circuit board. Each clip includes a horizontal top wall soldered to the printed circuit board and a horizontal bottom wall soldered to the PCB. A top arm formed integrally with the horizontal top wall has a linear contact area formed by a part that extends downwardly to the linear contact area and upwardly therefrom. A bottom arm formed integrally with the horizontal bottom wall has a linear contact area formed by a part that extends upwardly to the linear contact area and downwardly therefrom. The linear contact areas are spaced apart from one another by a distance that is slightly less than a thickness of a bimorph reed. A bimorph reed is slid between the two linear contact areas and is clampingly engaged by the inherent bias of the top and bottom arms.
Each clip, including its horizontal top and bottom walls and its top and bottom arms, is formed of an electrically conductive flexible and resilient material. The arms are inherently biased toward one another so that a bimorph when disposed in sandwiched relation therebetween, is clampingly engaged thereby.
The clips are positioned about mid-length of their associated PCB. Each bimorph reed is engaged near its trailing end by its associated clip. The respective leading ends of the bimorph reeds extend beyond the leading ends associated PCBs.
The Braille cell assembly of this invention includes a plurality of Braille cells, each of which preferably includes eight (8) Braille pins in a housing. Each pin is actuated to extend out of the housing by a bimorph reed. Thus, there are eight (8) bimorph reeds for each Braille cell. A first set of four (4) bimorphs are clippingly engaged to a first side of a printed circuit board to actuate a first column of four (4) Braille pins and a second set of four (4) bimorphs are clippingly engaged to a second side of the printed circuit board to actuate a second column of four (4) Braille pins.
In a preferred embodiment, twenty (20) printed circuit boards are mounted in a hollow frame structure, more particularly known as a chassis or backplane. As above-mentioned, each printed circuit board provides a mount for eight (8) bimorph reeds. Accordingly, each PCB drives one (1) Braille cell. In a preferred embodiment, known as a double decade, there are two (2) sets of ten (10) Braille cells mounted on the novel frame structure. Thus, there are twenty (20) PCBs and one hundred sixty (160) bimorph reeds mounted in the chassis/backplane. In a preferred embodiment, such collection of twenty (20) PCBs is considered a module. Each module is interconnectable with another module. Thus, a user may purchase one (1) module or any multiple thereof when purchasing a Braille display case. Advantageously, repairs are easily made by exchanging a good module for a broken or malfunctioning module so that a user need not purchase an entire Braille display case when a problem arises.
The chassis/backplane has a top wall, a bottom wall, a first, leading sidewall in the form of an angle wall and a second, trailing sidewall in the form of a flat wall. A horizontal section of the angle wall is disposed in abutting and coplanar relation to a leading edge of the frame top wall and the vertical section of the angle wall is disposed in abutting relation to the leading end of the frame bottom wall. The longitudinal extent of the frame top wall is thus less than the longitudinal extent of the frame bottom wall, the difference in longitudinal extents being equal to the longitudinal extent of the horizontal section of the angle wall.
The flat wall is disposed in abutting relation to the trailing edge of the top wall and the trailing edge of the bottom wall.
A plurality of sockets is mounted on the top wall of the frame, in depending relation thereto, with each socket having a trailing end disposed near a trailing edge of the top wall. Each socket is adapted to receive an upper, trailing longitudinal edge of an upstanding PCB.
A plurality of slots is also formed in the top wall to receive the respective leading ends of the PCBs.
Each PCB has a protuberance formed in its lowermost, trailing end. A corresponding plurality of slots is formed in the bottom edge of the flat wall of the frame to respectively receive the protuberances to thereby enhance the mounting of the PCBs within the frame.
A first plurality of clips is soldered to a first side of each printed circuit board and a second plurality of clips is soldered to on a second side of each printed circuit board as aforesaid. Each clip holds a bimorph reed in substantially parallel relation to the top and bottom walls of the frame and each center conductor of each bimorph reed is soldered to its associated PCB.
A plurality of sets of pinholes is formed in the horizontal section of the angle wall and each pinhole is adapted to slideably receive a Braille pin.
A first set of bimorph reeds clipped to a first side of a first PCB includes four (4) bimorph reeds having a common length. The bimorph reeds are staggered with respect to one another so that a leading end of a first, uppermost bimorph reed extends a first distance beyond a leading end of its PCB, a leading end of a second bimorph reed mounted below the first bimorph reed extends beyond the leading end of the first bimorph reed, a leading end of a third bimorph reed mounted below the second bimorph reed extends beyond the leading end of the second bimorph reed, and a leading end of a fourth bimorph reed mounted below the third bimorph reed extends beyond the leading end of the third bimorph reed.
A second set of bimorph reeds clipped to a second side of a first PCB also includes four (4) bimorph reeds having a common length. The bimorph reeds are staggered with respect to one another so that a leading end of a first, uppermost bimorph reed extends a first distance beyond a leading end of its PCB, a leading end of a second bimorph reed mounted below the first bimorph reed extends beyond the leading end of the first bimorph reed, a leading end of a third bimorph reed mounted below the second bimorph reed extends beyond the leading end of the second bimorph reed, and a leading end of a fourth bimorph reed mounted below the third bimorph reed extends beyond the leading end of the third bimorph reed.
Each bimorph reed is clipped to the printed circuit board so that a leading end of each bimorph reed is positioned beneath a Braille pin disposed in the pinholes formed in the horizontal section of the angle wall. The respective leading ends of the four (4) bimorph reeds on the first side of the PCB abut or are closely spaces apart from the lowermost ends of the pins in a first column of four (4) Braille pins in a Braille cell and the respective leading ends of the four (4) bimorph reeds on the second side of the PCB abut or are closely spaced apart from the lowermost ends of the pins in a second column of four (4) Braille pins in a Braille cell.
The Braille pins may be formed independently of one another or they may be formed in connected relation to one another so that one set of connected Braille pins is adapted to fit within one Braille cell. In the latter, eight Braille pins are releasably connected to one another so that individual pins of the set of connected Braille pins are detachable from one another after being placed into respective pinholes of a Braille cell.
Each pin of the plurality of Braille pins has a four (4) part construction. More particularly, each pin has a first, lowermost part of solid or hollow construction that may have a transverse cross-section of any predetermined geometrical configuration. A second part also has a solid or hollow construction that may have a transverse cross-section of any predetermined geometrical configuration but its breadth is greater than that of the first section. Accordingly, a first shoulder is formed where the first and second parts meet one another. A third part of the pin is of solid or hollow construction and may also have a transverse cross-section of any predetermined geometrical configuration. The breadth of the third part is less than the breadth of the second part, forming a second shoulder where said second and third parts meet. In a preferred embodiment, the third part has a non-circular cross-section such as a star-shaped cross-section, but any non-circular cross-section such as triangular, square, pentagonal, hexagonal, elliptical, oblong, crescent, and the like is within the scope of this invention.
The fourth part of each pin has a solid or hollow construction and may have a transverse cross-section of any predetermined geometric configuration. It has a breadth less than the breadth of the third part, thereby forming a third shoulder where said third and fourth parts meet. The fourth part includes a rounded free end adapted for tactile communication with a user of the inventive structure. The user feels the tip when the pin is extended, i.e., displaced from its position of repose by an actuated bimorph reed.
The tip of the first pin in the first column of pins is extended when voltage is applied to the uppermost bimorph reed in the first set of bimorph reeds. The tip of the second pin in the first column of pins is extended when a voltage is applied to the bimorph reed mounted immediately below the first bimorph reed. The tip of the third pin in the first column of pins is extended when a voltage is applied to the bimorph reed mounted immediately below the second bimorph reed and the tip of the fourth pin in the first column of pins is extended when a voltage is applied to the bimorph reed mounted immediately below the third bimorph reed.
The tip of the first pin in the second column of pins is extended when voltage is applied to the uppermost bimorph reed in the second set of bimorph reeds. The tip of the second pin in the second column of pins is extended when a voltage is applied to the bimorph reed mounted immediately below the first bimorph reed. The tip of the third pin in the second column of pins is extended when a voltage is applied to the bimorph reed mounted immediately below the second bimorph reed and the tip of the fourth pin in the second column of pins is extended when a voltage is applied to the bimorph reed mounted immediately below the third bimorph reed.
A monolithic cell cap covers each Braille cell of the plurality of Braille cells. It also covers a plurality of buttons that are dedicated to control of a cursor. More particularly, a first plurality of cursor-control buttons is mounted in upstanding to the top wall of the chassis/backplane. A first comb-like holder holds first plurality of buttons. Each button of the first plurality of buttons has a head and a stem, the head being enlarged with respect to its stem. The first comb-like holder includes parallel, contiguous teeth that are spaced apart from one another. The free end of each tooth is adapted to engage the heads of its associated button.
A second plurality of buttons is also mounted in upstanding relation to the top wall of the chassis/backplane. A second comb-like holder holds the second plurality of buttons. Each button of the second plurality of buttons has a head and a stem, the head being enlarged with respect to its stem. The second comb-like holder includes parallel, contiguous teeth that are spaced apart from one another. The free end of each tooth is adapted to engage the heads of its associated button. The first comb-like holder and the second comb-like holder are disposed in confronting relation to one another.
Each comb-like holder includes twenty (20) teeth. There being two (2) comb-like holders, there is a total of forty (40) buttons, i.e., two (2) buttons for each of the twenty (20) Braille cells in a module.
The bottom wall of the novel chassis/backplane is formed of a material that does not require additional isolation from the metal chassis to which it is mounted.
The monolithic cap that covers the first and second comb-like holders is releasably engaged to the top wall of the chassis/backplane. The monolithic cap has a first set of forty (40) openings formed therein to receive the respective heads of the buttons and a second set of one hundred sixty openings formed therein to receive the respective tips of eight (8) Braille pins of twenty (20) Braille cells when said tips are extended by actuation of their associated bimorph reeds.
The number of buttons and Braille cells may be changed to meet the requirements of various applications. The number of buttons and Braille cells of this illustrative embodiment is merely a preferred number.